Development of mobile phone and other portable device technology has meant that many of these devices are provided with a 3.5 mm (diameter) connector which allows them to connect with a combined headphone and microphone set. Typically these comprise a speaker for each ear and a microphone, usually provided as a medallion. The connectors, or sockets, (of the mobile phone/portable device technology) for such sets are provided with four terminals, as is the set's plug/pin.
An issue arises that different manufacturers configure the contacts of the plug differently. Manufacturer A may have the microphone contact as an inner terminal whereas manufacturer B may have the microphone on the outer terminal. In an aircraft seat with inflight entertainment, passengers often chose to listen to the audio provided using their personal headphones, rather than the ones provided by the airline. Sometimes the passenger will desire to use his/her combined headphone/microphone set which has a four contact plug. Because the audio socket module in the aircraft is normally configured with only three terminals, use of a plug with four contacts creates an incompatibility that results in loss of either left or right audio when a combined headphone/microphone is connected.
We have devised an improved socket for headphone sets.